Pure algae growth system and method

ABSTRACT

A tank receives, mixes, and dispenses input materials including algae feed stock, a micro-nutrients, cleaning solution, a sterile gas, a heating/cooling fluid, carbon dioxide, and raw water with a water treatment system. A plurality of output stations include a vent to atmosphere, a heating/cooling media return, a cleaning disposal, and an algae concentrate/product. The vent to atmosphere is coupled to the tank. The heating/cooling media return is coupled to the heating/cooling media supply through the tank. The cleaning solution disposal station is coupled to the tank with a pump followed by a nano bubbler and an algae growing system. An algae concentrate/product station is coupled to the tank. An algae dewatering system is intermediate the tank and the algae concentrate/product. A water return line couples the algae dewatering system and the water treatment system.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of copending U.S. patentapplication No. 15/184,394 filed on Jun. 16, 2016, now U.S. Pat. No.10,208,276, which in turn claims priority to U.S. ProvisionalApplication No. 62/230,850, which was filed in the United States Patentand Trademark Office on 17 Jun. 2015, the disclosures of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a pure algae growth system and methodand more particularly pertains to growing algae in a safe, convenient,and economical manner.

Description of the Prior Art

The use of algae growing devices is known in the prior art. Morespecifically, algae growing devices previously devised and utilized forthe purpose of growing algae are known to consist basically of familiar,expected, and obvious structural configurations, notwithstanding themyriad of designs encompassed by the crowded prior art which has beendeveloped for the fulfillment of countless objectives and requirements.

LITERATURE CITED

The following references and others cited herein but not listed here, tothe extent that they provide exemplary procedural and other detailssupplementary to those set forth herein, are specifically incorporatedherein by reference.

-   US PATENT DOCUMENTS; U.S. Pat. Nos. 4,253,271; 5,104,803; and    5,958,761-   OTHER PATENT DOCUMENTS; WO00174990, WO1999046360

OTHER PUBLICATIONS

-   Chen C Y, Liu C H, Lo Y C, Chang J S. 2011. Perspectives on    cultivation strategies and photobioreactor designs for    photo-fermentative hydrogen production. Bioresource Technology    102:8484-8492.-   Feng P, Deng Z, Hu Z, Fan L. 2011. Lipid accumulation and growth of    Chlorella zofingiensis in flat plate photobioreactors outdoors.    Bioresource Technology 102:10577-10584.-   Feng P, Deng Z, Fan L, Hu Z. 2012. Lipid accumulation and growth    characteristics of Chlorella zofingiensis under different nitrate    and phosphate concentrations. Journal of Bioscience and    Bioengineering 114:405-410.-   Pinker R T. 1995. Estimating Photosynthetically Active Radiation    (PAR) at the earth's surface from satellite observations. Remote    Sensing of Environment 51:98-107.-   Guil Guerrero J L, Rebolloso-Fuentes M. 2008. Nutrient composition    of Chlorella spp. and Monodus subterraneus cultured in a bubble    column reactor. Food Biotechnol 22:218-233.-   Hall D O, Fernandez F G, Guerrero E C, Rao K K, Grima E M. 2003.    Outdoor helical tubular photobioreactors for microalgal production:    modeling of fluid-dynamics and mass transfer and assessment of    biomass productivity. Biotechnology and Bioengineering 82:62-73.-   Heinrich J M, Niizawa I, Botta F A, Trombert A R, Irazoqui    H A. 2012. Analysis and design of photobioreactors for microalgae    production II: experimental validation of a radiation field    simulator based on a Monte Carlo algorithm. Photochemistry and    Photobiology 88:952-960.-   Jung E E, Jain A, Voulis N, Doud D F, Angenent L T,    Erickson D. 2014. Stacked optical waveguide photobioreactor for high    density algal cultures. Bioresour Technol 171:495-499.-   Lane C, Hapel K, Rismani-Yazid H, Kessler B A, Moats K M, Park J,    Schwenk J, White N M, Bakhit A, Allnutt F. 2014. Final    Scientific/Technical Report—DOE Award DE-FE0001888 Beneficial CO₂    capture in an integrated algal biorefinery for renewable generation    and transportation fuels. DOE-NETL.-   Lee Y-K. 2001. Microalgal mass culture systems and methods: Their    limitation and potential. J Appl Phycol 13:307-315.-   Perez M, Nolasco N, Vasavaa A, Johnson M, Kuehnle A. 2015.    Algae-mediated valorization of industrial waste streams. Industrial    Biotech 11:229-234.-   Priess M, Kowalski S. 2010. Algae and Biodiesel: Patenting Energized    as Green Goes Commercial. J Comm Biotech Bioengineering 16:293.-   Sato R, Maeda Y, Yoshino T, Tanaka T, Matsumoto M. 2014. Seasonal    variation of biomass and oil production of the oleaginous diatom    Fistulifera sp. in outdoor vertical bubble column and raceway-type    bioreactors. Journal of bioscience and bioengineering 117:720-724.-   Sheehan J, Dunahay T, Benemann J R, Roessler P. 1998. A look back at    the US Department of Energy's Aquatic Species Program: Biodiesel    from Algae. National Renewable Energy Laboratory.-   Ugwu C U, Ogbonna J C, Tanaka H. 2002. Improvement of mass transfer    characteristics and productivities of inclined tubular    photobioreactors by installation of internal static mixers. Applied    microbiology and biotechnology 58:600-607.-   Van Den Hoek C, Mann D G, Jahns H M 1995 Algae: An Introduction to    Phycology. Cambridge University Press.

While known devices fulfill their respective, particular objectives andrequirements, they do not describe a pure algae growth system and methodthat allows growing algae in a safe, convenient, and economical manner.

In this respect, the pure algae growth system and method according tothe present invention substantially departs from the conventionalconcepts and designs of the prior art, and in doing so provides anapparatus primarily developed for the purpose of growing algae in asafe, convenient, and economical manner.

Therefore, it can be appreciated that there exists a continuing need fora new and improved pure algae growth system and method which can be usedfor growing algae in a safe, convenient, and economical manner. In thisregard, the present invention substantially fulfills this need.

SUMMARY OF THE INVENTION

In view of the disadvantages inherent in the known types of algaegrowing devices now present in the prior art, the present inventionprovides an improved pure algae growth system and method. As such, thegeneral purpose of the present invention, which will be describedsubsequently in greater detail, is to provide a new and improved purealgae growth system and method which has all the advantages of the priorart and none of the disadvantages.

To attain this, from a broad perspective, the present inventionessentially comprises a tank for receiving, mixing and dispensing inputmaterials. The input materials include algae feed stock, amicro-nutrients supply, a cleaning solution, a sterile gas, aheating/cooling fluid, a carbon dioxide supply, and a raw water supplywith a water treatment system. A plurality of output stations includes avent to atmosphere station, a heating/cooling media return station, acleaning disposal station, and an algae concentrate product station. Thevent to atmosphere station is coupled to the tank. The heating/coolingmedia return station is coupled to the heating/cooling media supplythrough the tank. The cleaning solution disposal station is coupled tothe tank with a pump followed by a nano-bubbler and an algae growingsystem. An algae concentrate/product station is coupled to the tank. Analgae dewatering system is intermediate the tank and the algaeconcentrate/product station. A water return line couples the algaedewatering system and the water treatment system.

There has thus been outlined, rather broadly, the more importantfeatures of the invention in order that the detailed description thereofthat follows may be better understood and in order that the presentcontribution to the art may be better appreciated. There are, of course,additional features of the invention that will be described hereinafterand which will form the subject matter of the claims attached.

In this respect, before explaining at least one embodiment of theinvention in detail, it is to be understood that the invention is notlimited in its application to the details of construction and to thearrangements of the components set forth in the following description orillustrated in the drawings. The invention is capable of otherembodiments and of being practiced and carried out in various ways.Also, it is to be understood that the phraseology and terminologyemployed herein are for the purpose of descriptions and should not beregarded as limiting.

As such, those skilled in the art will appreciate that the conception,upon which this disclosure is based, may readily be utilized as a basisfor the designing of other structures, methods and systems for carryingout the several purposes of the present invention. It is important,therefore, that the claims be regarded as including such equivalentconstructions insofar as they do not depart from the spirit and scope ofthe present invention.

It is therefore an object of the present invention to provide a new andimproved pure algae growth system and method which has all of theadvantages of the prior algae growing devices and none of thedisadvantages.

It is another object of the present invention to provide a new andimproved pure algae growth system and method which may be easily andefficiently manufactured and marketed.

It is a further object of the present invention to provide a new andimproved pure algae growth system and method which is of durable andreliable constructions.

An even further object of the present invention is to provide a new andimproved pure algae growth system and method which is susceptible of alow cost of manufacture with regard to both materials and labor, andwhich accordingly is then susceptible of low prices of sale to theconsuming public, thereby making such pure algae growth system andmethod economically available.

Lastly, it is an object of the present invention to provide a pure algaegrowth system and method for generating pure algae therefrom. Thefeeding of the input materials and the generating of the pure algae isdone in a safe, convenient, and economical manner.

These together with other objects of the invention, along with thevarious features of novelty which characterize the invention, arepointed out with particularity in the claims annexed to and forming apart of this disclosure.

For a better understanding of the invention, its operating advantagesand the specific objects attained by its uses, reference should be hadto the accompanying drawings and descriptive matter in which there isillustrated preferred embodiments of the invention.

The invention will be better understood and objects other than those setforth above will become apparent when consideration is given to thefollowing detailed description thereof. Such description makes referenceto the annexed drawings wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the exemplary embodiments of the inventionwill be had when reference is made to the accompanying drawings wherein:

FIG. 1—Process Schematic. This displays an overall schematic of onepossible configuration of the Pure Algae Growth Systems process and itscomponent systems of the instant invention. This configuration consistsof material inflows which can be characterized as: 1) a sterile, inertgas which acts as both a “blanket” which blocks intruding as—Invadersand provides media cooling when necessary by a novel in situ evaporationprocess; 2) a feed gas which contains CO₂ (carbon oxide) which can bepure or a by-product several industrial processes; 3) water which can beof considerable impurity as all of it must be treated to a high levelprior to coming into contact with the micro algae; 4) algae feed stockwhich actually inoculates the growing process; 5) various micronutrientswhich all growing things require to grow and multiply. This stream couldalso consist of simple sugars which micro algae during non-daylighthours; 6) cleaning solution which must be used when the micro algaespecies growing is to be changed; 7) heating/cooling media whichsometimes could be required if growing conditions (temperature) are lessthan ideal. This material does not contact the actual algae itself butis present, when needed, in the surge volume or tank “jacket”.

The material outflows shown consist of: 1) a vent to the atmospherecontaining the sterile inert gas blanket material which now containswater from evaporation via contact of the actual algae growing media; 2)the heating/cooling media which is recycled and tempered prior to itsreintroduction (this is only a temporary flowing stream); 3) cleaningsolution which must be processed prior to ultimate disposal (this isonly a temporary flowing stream); and 4) the final micro algae productwhich has been concentrated to some level based on the actual operator'sfinal customer specification. These systems are further described incomponent system drawings and specifications.

FIG. 2—Pure Algae Growth System Module. This displays an overallschematic of one possible configuration of the Pure Algae Growth Systemsoperating system. This configuration has ten actual photobioreactors.They exist as five “down and back” flow paths operated in a parallelmanner. This feature allows the system to expand without the need oftransferring to another physical location as the volume of the microalgae culture grows. These five flow paths make up one module and thesupporting components of the system can accept as many as ten (total) ofthese modules using the same surge volume or tank and ancillarycomponents. This feature provides significant economies of scale for therequired component capital costs. This one module is also used as a basecomparison for competing commercial system costs, both operating andcapital.

FIG. 3—Typical Commercial System. This displays an overall processschematic of a commercial raceway type micro algae growing system. Thissystem is “sized” such that one such system can be harvested in a dayand yield the equivalent amount of biomass (algae) as the Pure AlgaeGrowth System which is described in FIG. 2 above. For equivalent yield(to an invention module), accounting for—the necessary steps associatedwith a raceway type configuration; twenty-one actual raceway systemsmust be employed. This allows time for the necessary inoculation,growth, harvesting, and cleaning operations which must occur.

FIG. 4—Design criteria for acceptable tubular modular light reactors.The pressure exerted from the inside of the modular light reactorsdictates the required tensile strength of the material used in theirconstruction. The system is based on a nominal 100-millimeter diametertube with a 1-millimeter wall thickness. The required media flow ratesinside the tube result in a maximum pressure inside the tube of 20lbs/square inch which requires a working tensile strength of 2,000lbs/square inch.

FIG. 5 Graphic Depiction. This is a semi-logarithmic graph displayinghow various polymeric materials tolerate and respond to the internalpressure of the material flowing inside. This graph uses the100-millimeter tube with a 1-millimeter wall thickness as an example andseveral commercially available polymeric materials stress tolerance aresuperimposed upon the graph. It provides the base design criteriaoutlined in FIG. 4 above and shows why the polyurethane polymer waschosen for the operating system.

FIG. 6—Test Results. This displays the test results of 800 hours ofheli-arc light exposure to polyurethane polymeric material which is tobe used in the described invention. This test mimics the equivalent ofsunlight in a tropical environment and is likely more severe than theactual real time use of the material in such an environment. Thisinformation substantiates the claim of long duration expected use of thepolyurethane material in actual practice.

FIG. 7—Process Water System. This system shows how raw water isintroduced and processed to the needed degree of cleanliness. Thiscleanliness factor ensures that foreign bodies or contaminants are keptout of contact with the algae. This cleaning operation consists ofmultiple filtrations followed by an ultra violet light sterilizationtreatment. All water that enters the system is treated prior to actualuse.

FIG. 8—Sterile Gas System. This system provides the required gas foracting as a protective blanket keeping intruders out of the system.Because the incoming gas is essentially dry it can provide the coolingnecessary to keep the media within ideal temperature operating ranges.This cooling is done by evaporating a small portion of the media waterand the evaporated water “carries” the surplus heat from the system andis rejected to the environmental atmosphere. This sterile gas can besurplus nitrogen from an operating air separation facility or simpleambient air which must be dried, compressed and sterile filtered priorto use. Both systems are shown in schematic form.

FIG. 9—Gaseous Carbon Dioxide (CO₂) System. This system displays thenormal feed stock for a photosynthetic microalgae growing system. Thecarbon dioxide can be from “bottled” or previously extracted and refinedor waste CO₂ which can be found in any number of industrial processeswhich are presently vented to the atmosphere. The invention process canutilize any number of gases as long as the volume or mole % carbondioxide is at least 20% and no heavy metals, which will contaminate theproduct algae, are contained. Typical industrial waste gases containingcarbon dioxide are released to the atmosphere and these must becompressed to 2-3 atmospheres of pressure. This process often bringscorrosion issues which have been solved previously by operating astandard air compressor in a mode which does not allow the compressedgas to condense any water that may exist with the incoming gas.

FIG. 10—Dewatering System. This system concentrates the grown algae to alevel specified by the ultimate customer depending on final product use.Currently the system uses either cross flow filtration, developed forthe pharmaceutical industry, or a modified centrifugation process. Boththese candidates are available from several commercial sources and theactual system will be specified for each individual customer.

FIG. 11—Seed Stock and Nutrient Introduction System. This systemconsists of a mixing or blend tank and introduction pump. The materialsare first fabricated to the desired concentration and then introduced tothe surge tank in the invention system. The high turbulence of thesystem ensures that the material is most immediately blended andavailable to the entire growing media volume.

FIG. 12—Modifications/Additions Required for True Mixotrophic Growth.This schematic shows the required addition. It consists of a mix tankwhich blends the simple carbohydrate and a pump which introduces it tothe actual algae growing system. This allows 24/7 growth and enablesvarious current waste streams to be converted into useable microalgaebiomass.

FIG. 13—Media Heating/Cooling System. This schematic shows a typicalsystem that would allow media heating/cooling during non-optimal times.The plan is to use a mixture of propylene glycol and water as the actualheat transfer medium and an external heat source. The source could be anindustrial size heat pump because of the relative low temperatureextremes required. The propylene glycol was selected because of itsphysical characteristics, i.e. miscibility with water, boiling point,freeze point etc. and more importantly because of its overall lowtoxicity to living things. This material is often used as diluents incontact medications for humans.

The same reference numerals refer to the same parts throughout thevarious Figures.

DETAILED DESCRIPTION OF THE INVENTION

Open microalgae growing systems currently being used for commercialproduction of algal biomass and bioproducts largely mimic ponds anddrainage ditches.

Open raceway technology circulates growth medium around an oval trackthat is often powered by a paddlewheel that serves to drive the mediumaround the oval raceway, mix the culture and aerate the growth medium.Good examples of commercial systems based on raceway algal culture arethe production systems of Cyanotech (Kona, Hi., USA) and Seambiotic Ltd.(Ashkelon, Israel).

Enclosed microalgae growing systems currently at commercial orpilot-scale are largely of two types—glass tubes (such as theastaxanthin systems used by Algatechnologies, Ltd. located in Eilot,Israel) and plastic disposable hanging tubes (such as used by Algenol,Inc. located in Ft. Meyers, Fla., USA). Both approaches depend on thepresence of the needed nutrients, seed stock and carbon sources. Thesecomponents will be processed by the microalgae and form the biomasswhich will accumulate until competitive forces or a nutritionallimitation impede maximal microalgal growth. This competition could befrom other non-target microalgal strains or various competitors andpredators that find the microalgae a suitable diet (such as protozoansand crustaceans). Or the competition can be their own cells as theybecome denser and shade each other they compete for the sun's energyself-shading). These factors are seen today in the microalgae growingindustry with predictable results as outlined above.

The current invention, the Pure Algae Growth System (PAGS), seeks toovercome existing constraints by utilizing proven industrial unitoperations that guarantee an environment that offers control of thespecies of microalgae being grown, reduces contamination by competitorsand predator species, and optimizes the environment for algalcultivation. Additionally, most current microalgae growing systemsoperate in a batch mode with significant time required for startup,cleaning and etc. All these conditions are non-productive and this isreflected in the cost of algal biomass produced. The current inventionhas several novel features which minimize these penalties. Thesefeatures include: easy scale up within an enclosed loop, pressurizedreactors, continuous operation, and in situ cleaning whenever required.

The present invention is an innovative microalgal culturing systemcomprising a pressurized mixing and recycling chamber, pressurizedmodular light reactors enclosed in transparent or translucent materials,and a liquid pumping system capable of circulating the algal cultures inturbulent flow greater than a Reynold's Number of 10,000. Thepressurized mixing chamber is used to assure that introduced inputs(e.g., macro- and micronutrients, fresh medium, and makeup water) areefficiently and homogeneously distributed throughout the entire system.Additionally, the missing and recycling chamber allows efficientintroduction of carbon dioxide (CO₂) and removal of excess oxygen (O₂).The pressurized missing and recycling tank provides the pressure neededto drive the algal culture into the modular light reactors and throughthe entire loop for return to the mixing tank. The applied pressureexpands the modular reactors and ensures that any transfer of materialsor gases is out of the culture system, thereby reducing the chance forcontamination.

The process schematics of one Pure Algae Growth System of the presentinvention design, as shown in FIG. 1, define a pure algae growth systemapplicable to many varied end uses. Modifications of the presentinvention will be made as needed to ensure that: 1) the end use of themicroalgae is taken into account, e.g., human food applications willneed to match regulatory requirements; 2) requirements of the culturedspecies are met, e.g., specific growing conditions such as nutrients andlight; and 3) the type of dewatering required, e.g., filamentous versussingle celled algae. Additional modifications will be required toaccommodate different raw materials such as use of non-potable water,waste waters, addition of fixed carbon substrates, or use of industrialcarbon dioxide emissions. All these process equipment additions ormodifications are physically known and used in other processes and canbe added to the present invention with no or minimal operational risk.

Modular Light Reactors. System Startup—Scaled up current microalgaegrowing operations proceed in a batch wise fashion. By necessity thesecultures must start at a test tube level and proceed to perhaps amillion liters of active culture. Typically, cultures of increasingscale are grown outside and therefore each successive batch “growth”must be less than 100 times the parent's volume. This allows the wantedculture a numerical advantage over the “wild” strains that are alwayspresent.

These factors force a typical scale up, from test tube to a millionliters, to require several weeks with associated loss of systemproduction and increased susceptibility to culture crashes andnon-productive contaminated media disposal. The current invention isdesigned to minimize or eliminate these hazards by its construction,operation and contamination safeguards. The modular light reactors canbe made with flexible or rigid translucent or transparent materials thatallow optimal light penetration for maximal photosynthesis.

Additionally, these reactors are designed to be brought into theproduction cycle sequentially when the culture density has reached anoptimized level. This sequential introduction of additional lightreactor modules, facilitated automatically through the mixing andrecycling chamber (essentially a manifold), removes the need for serialtransfers to larger and larger culture volumes (with associated pumpingand chance of contamination) as most often applied in current racewaysystems and enclosed photobioreactors. The PAGS system is also designedto deliver turbulent flow in the modular light reactors that providessignificant advantages to the algal production process. This turbulentflow circulates the algae at flow rates greater than a Reynold's Numberof 10,000. This flow minimizes the amount of time that the algae spendin the interior of the culture, where light levels are limiting. It alsoprovides a scouring effect on the inner walls of the modular lightreactors to minimize the accumulation of biofilms (which reduce lightand are sites of bacterial amplification). The turbulent flow alsomaximizes the mixing of gas bubbles containing the CO₂ to keep the gasand algal cells in better contact, thereby maximizing the available CO₂for cellular growth. The above features allow the use of simple sugarsto act as food when sunlight is not available. The quick response of thePAG process will allow residual CO₂ to be stripped from the medium inapproximately 4 minutes and simple sugars introduced as replacementfood. This is a unique feature of PAGS which permits operation in a truemixotrophic mode. Typically, the use of fixed carbon growth process(heterotrophic growth) is much faster than the phototropic processallowing more than doubling of the biomass yield on a daily basis.

Materials of Construction—Current microalgae growing systems employmaterials of construction that are normally disposed of after use. Thisinvention uses robust materials to build the modular light reactors thatare tolerant to sunlight, nearly identical to water in lighttransmission and can be repaired in place. This robustness translates toless lost production time and a lower unit cost for the algae.

Careful selection of the plastic to be used in the modular lightreactors is required to provide maximal light transmission in the PARregion, withstand continuous assault from UV in sunlight, withstand thepressure supplied internally by the system and be simple to work with. Adescription of the parameters being met by the materials used to makethe modular light reactors is provided in FIG. 4.

Growing algae in flexible polymeric tubes requires major compromises. Alarge volume, hence big diameter, would seem to increase the potentialgrowth rate. However, increases in growth are limited by the amount ofsunlight that is available and for high density cultures only a small“rim” nearest the sunlight is actively growing.

Even with extreme turbulence, a diameter representing the best economictradeoffs (capital cost, performance and robustness) is required. Pastexperimental work in Hawaii indicates that an outside diameter of about100 mm represents the best solution for low latitude outside culturing.The diameter is small enough to allow known plastics to provide therequired tensile strength and existing polymer extruders can producetubes of sufficient wall thickness and quality to allow use.

Fully developed turbulent flow within the tube requires the use ofmaterials with a tolerance of the required pressures. The tube will failin hoop stress, which can be represented by the equation: tau (sheartensile force)=Pressure (PSIG)×Diameter (length)/Wall Thickness(length).

Using our selected tube diameter of 100 mm about 10 cm (4 inches) and areasonable wall thickness [about 1 mm (0.040 inches)] and an internalpressure 20 PSIG yields a required tensile strength of 13.6×10⁶ Pa(2,000 lb/in²). This is a required working tensile strength and a safetyfactor of 2-3 must be included to allow for imperfections in the polymerand the extrusion process itself.

Olefins fail this required tensile capability and are therefore notuseful for this invention. It is common to extrude polyethylenes (bothhigh and low density) and polypropylene. These materials are relativelyinexpensive and are true plastics. Plastic is derived from the ancientGreek word, plastikos, which roughly translates to formable. The olefinshave no true elastic range; this is when stressed by internal pressureactually returns to its original shape and dimensions. They immediatelybegin to yield and the diameter increases. This causes the wall tobecome thinner, as the diameter increases, and catastrophic failureoccurs almost immediately. The obvious answer is to increase the wallthickness of the tube. However, this degrades light transmission andmakes the tube heavier and more expensive. Also, the extrusion processbecomes more difficult and a final wall thickness of about 0.040″ isabout the practical limit for most known plastics.

Suitable tensile strength polymers could include nylons, super strengthultra-high mole polyethylene and a class of compounds known aspolyurethanes. Also, the positive pressure of the system ensures that itwill “leak out”; if minor failures occur preventing intrusion andsubsequent contamination during repair operations. Nylons do nottransmit light well and the ultra-high molecular weight polyethylene hasnot been successfully extruded as yet (their use is presently limited tohigh value items such as armor plate and bullet proof vests) forpersonal protection.

Polyurethane is formed by reacting an isocyanate with various chainlength polyols (contain multiple OH groups). It is known how to tailorthe desired flexibility and tensile strength and apply using extrusiontechnology has been around for years. Polyurethane tensile strength(typically shown as ultimate) is listed at about 10,000 lbs/in² whichwould allow a safety factor of about 4-5 for this application.Ultraviolet light resistance is high for these compounds and exposure tofull Hawaii sun for 4-5 months was found to only cause slight yellowingand no apparent degradation of tensile capability.

The strain expected on the materials in the wall of the modular lightreactors is graphed in FIG. 5. Since the predicted requirement fortensile strength is 2000 lbs./square inch, it is obvious from FIG. 5that LDPE and HDPE are not appropriate for use in the PAGS system. Thecurrent materials used in the FAGS pilot system are a proprietarypolyurethane produced by Nu-Methods (Cuyahoga Falls, Ohio, USA). It is aseamless tubing, custom formulated using a polyurethane blend with aproprietary UV resistance package and does not contain phthalates. Theresin can be extruded as tubing, blown film and heavier wall (1 mm)sheet/roll goods as needed. It is FDA-acceptable a d EU food safe fordirect food contact and packaging. It was tested for high lightstability using an 800-hour heli-arc light exposure test (FIG. 6). Thispolyurethane shows very minimal to almost no darkening and should remainviable for over a year in the modular light reactor.

Culture Density—Current commercial microalgae growing systems havelittle overall agitation or must spend significant additional energy(cost) to accomplish this. The mixing is required because only a verysmall region of the actual existing system has the right mix of photons,nutrients and other necessary materials.

Also, in existing commercial systems significant temperature variationsin the medium adversely affect overall growth rates. The invention usesfully turbulent flow in the modular light reactors, which greatlyimproves the overall system growth rate and allows higher culturedensity. This higher density requires a much less expensive dewateringstep later on when the microalgae are actually converted to a commercialproduct.

Growing Environment Current microalgae systems are largely grown outsideand are exposed to natural contamination from wind or other surfaceborne contamination sources. The invention grows the microalgae in acontrolled environment that is free of contamination sources by design.This factor in conjunction with the proven initial feed stock guaranteesa healthy culture which can multiply at an accelerated rate. Theinvention also allows food and nutrients to be introduced at apredictable rate which insures optimum growth rate.

Mixing and Recycling Chamber/Temperature Control The mixing and recyclechamber (surge tank) has several uses and is the process control centerof the PAGS system. These uses include:

-   -   a. Removal of the oxygen generated during the previous cycle or        passage through the growing tubes. Forced removal of the product        oxygen encourages the desired reaction to proceed more quickly        than competing systems.    -   b. Cooling of the media which may adversely affect the        photosynthesis process; if temperatures above 35° C. are        reached. This cooling is done in the same process as the oxygen        removal and can be adjusted to maintain optimal growing        temperatures by adjusting the flow rate of the dry gases that        are being introduced into the surge tank.    -   c. Heating of the media if the temperatures of 20° C. or lower        are reached during cold periods or via night time cooling. This        improves system or growth rate startup as all reaction rates        will increase with higher reaction temperatures.    -   d. Introduction of required micronutrients or vitamins that may        be needed for optimum growth rates.    -   e. Acting as a central control volume where process variables        are measured and appropriate actions are initiated. The quick        response time for the entire system maintains optimal growth        conditions.    -   f. Provides a surge volume suitable for multiple photobioreactor        modules. The single point of control for all growing modules        encourages optimal growth conditions and significant capital        cost savings.

These specific functions are described briefly below:

-   -   a. Oxygen Removal—The oxygen formed during the photosynthesis        process is removed via stripping by sparging with small bubbles        of elemental nitrogen. This process is used industrially and        specific ratios are known for oxygen removal. This encourages        our desired photosynthesis reaction and will improve drastically        the overall biomass growth rate.    -   b. Media Cooling—The temperature of media will increase during        the photosynthesis process. This increase is largely due to        infrared heating from the sunlight. The cooling process will        occur because the bone dry nitrogen which is used for positive        pressure maintenance in the system will actually vaporize some        water and carry it out of the system. Water has a latent heat        capacity of about 2.2×10⁶ J kg⁻¹ (1,000 BTUs per pound) and the        bone-dry nitrogen will exit with about 5 mole percent water at        the expected temperatures. The flow rates of the nitrogen can be        adjusted to maintain optimal media temperature for growth. This        is done by sparging nitrogen (which is bone dry) contained in        very small bubbles. The nitrogen has very low solubility at this        pressure and in addition to stripping the product oxygen it will        evaporate water as well. The latent heat of water is high (about        1,000 BTUs/lb.) and this evaporation will cool the media to a        desired growing temperature. The nitrogen acts as an in-situ        cooling tower. Commercially nitrogen produced by a cryogenic        separation process from air is often a surplus product that can        be obtained at little capital cost. The separation process        ensures that it is both sterile and bone dry; both features        needed for this application.    -   c. Media Heating—The temperature of the medium could drop below        the optimal growing range. This could be caused by night time        cooling via radiation or actual cold air temperatures.        Temperature adjustment will be done using a mixture of        polypropylene glycol and water in the jacket of the surge tank.        Polypropylene glycol is much less toxic to living things and is        often used as diluents in pharmaceutical preparations.    -   d. Required Micronutrient Addition—These items will be consumed        during photosynthesis process and can be added directly to the        system via the surge tank.    -   e. Central Process Control—The PAGS system will have very short        response times. This is because the medium is circulated very        rapidly, and the process variables will essentially be real time        for very nearly the entire system. This is very different than a        large open pond where actual circulation may be measured in        hours. This feature will allow the entire system to be        maintained at optimal growing conditions regarding process        variables and reactant concentrations.    -   f. Required Surge Volume—Each photobioreactor module pump will        transfer medium in the hundreds of liters per minute flow rates.        Additional modules will require the availability of a        significant “heel” in the tank to ensure that all pumps will not        be starved or cause cavitation. The surge tank is designed and        specified such that up to 10 modules can be served by one tank.        This feature will allow significant economies of scale and        capital cost reductions which do not exist in the conventional        open pond set up.    -   g. Carbon Dioxide Utilization—The PAGS process uses pressurized        carbon dioxide in a contained space. This results in as much as        a 20-fold improvement in carbon dioxide utilization over        existing commercial systems. The technique was first used at a        commercial installation in Hawaii where the carbon dioxide was a        waste stream from an industrial process (a naphtha reformer).        This installation was developed based on an EPA grant award for        novel sourcing of microalgae feedstock. This initial concept has        been improved by locating superior materials of construction for        the actual microalgae growing volumes. This capability affords a        much broader choice of waste gases for the microalgae food.        Volume or mole percentages as low as 25% carbon dioxide will        provide adequate food stock with minimal degradation in carbon        dioxide utilization.

The modifications required for the PAGS process to utilize this lowerquality food are merely slight increases in the gas handling systems.

Current microalgae systems use carbon dioxide (which must be dissolvedin the growth medium) or a simple carbohydrate as food for promoting thealgae growth. Existing algae growth systems are open to the atmosphereand normally very shallow making introduction of CO₂ difficult andreducing off-gassing also difficult. Feed materials, such as gaseouscarbon dioxide, are introduced with little opportunity to beincorporated in the algae growth medium and most CO₂ is simply vented(lost) to the atmosphere. The PAGS system is closed and under as much as2 bars of pressure. This greatly increases the solubility of the carbondioxide, which permits the algae to more efficiently take it up andchannel it to enhanced growth.

The carbon dioxide could be naturally occurring or introduced as amixture of gases. In either case the utilization of the carboncontaining food is quite low. If introduced as a gas, previousgeometries of the algae growing systems almost insured that most of itis wasted and vented. The current invention uses a higher partialpressure of the carbon dioxide to enhance the dissolving process. Theresult is high food utilization and its attendant reduced componentcost. Currently, the PAGS system uses high concentration CO₂ to chargethe system and flushes out excessive oxygen with nitrogen or inertgases. When any gas is in contact with water, some gas will dissolve inthe water. The amount that will dissolve in the water depends on thepressure (or partial pressure if the gas is a mixture) and temperature.Gas solubility (the amount that can be dissolved) is inverselyproportional to the temperature.

Henry's law quantifies this relationship and has been used to design andcharacterize functioning industrial processes where mass transfer from agas to a liquid is an inherent part. A table of measured Henry's Lawconstants is shown below for some common gases at a temperature of 25°C. (Table 1).

TABLE 1 Values of various gases at 20° C. K(h) Gas (atm/mole) Oxygen(O₂) 769.23 Hydrogen (H₂) 1282.05 Carbon Dioxide (CO₂) 29.41 Nitrogen(N₂) 1639.34 Helium (He) 2702.7 Neon (Ne) 222.22 Argon (Ar) 714.28Carbon Monoxide (CO) 1052.63

Using these constants, what the concentration of N₂ in water (with apure N₂ atmosphere)?

K (h for N₂)=1639.34=P (N₂)/(N₂ aqueous)=1 atmosphere/X

a. X=6.1.×10⁻⁴=0.00061 moles/volume

Since air is 78% N₂ (by volume or moles)

a. X′=0.00061×0.78=0.00048 moles/volume

CO₂ is much more soluble than nitrogen and for a pure CO₂ atmosphere

K (h for CO₂)=29.4=2002/(002 aqueous)=1 atmosphere/X

a. X=0.034 Moles/Volume almost 100 times the concentration of nitrogen

In the PAGS system the pressure at the CO₂ introduction is approximately2 atmospheres (of pure CO₂) and therefore the equilibrium value isnearly 0.068 Moles/volume. We will be introducing only a small fractionof that amount (roughly what the algae can consume during their “visit”to the photon source) and the nanobubbler device will ensure visiblebubbles will rarely if ever be seen.

Oxygen is generated during the photosynthesis process. Thephotosynthesis reaction (as are all reactions) is reversible and thepresence of oxygen will slow the overall desired reaction. The productoxygen will be largely removed from the media by stripping with gaseousnitrogen in the surge tank. This technique is commonly used in industryand very low residual oxygen concentrations can be attained. Someunreacted CO₂ will also be stripped but its superior solubility (26times that of oxygen) will minimize this loss.

The projected utilization of CO₂ is perhaps 20 times better thanexisting systems. The actual growth rate of biomass will also besignificantly better than existing systems. This is because of theoptimal growing conditions in the FAGS process:

a. High pressure and equilibrium solubility for the dissolving process

b. Preferential removal of oxygen for the reverse reaction.

As new technologies are produced to separate gases economically,recovery and recycling of the CO₂ when the oxygen is purged couldimprove the carbon balance of this system. Unfortunately, currenttechnologies are not available for this process.

This same recycle feature is possible with the micronutrients andmacronutrients that are not consumed and remain in the spent algaegrowing medium. These compounds are simply carried along with the wateron dewatering and can then be recycled for further growth. Componentutilization efficiencies with the PAGS system are perhaps 10 timesexisting systems.

Any gas introduced to stimulate algae growth must first be dissolved inthe algae growing media. Existing systems have a simple “sparge” devicewhich produces large bubbles of gas. These bubbles have significantbuoyant forces and simply rise quickly to the surface and are vented andlost. The PAGS system uses unique nanobubblers which produce very smallbubbles. These bubbles have very high surface area to volume ratioswhich yield very productive mass transfer rates (and associated highmaterial utilization and efficiencies).

The PAGS design maintains carbon dioxide in solution phase over theentire length of each modular leg through a novel introduction andretention system. The CO₂ is introduced as a nanobubble in the mixingand recycling chamber under pressure higher than atmospheric. The CO₂loaded culture is passed into the modular light reactor and turbulentlymixed throughout its entire passage, thereby ensuring any CO₂off-gassing is prevented.

System Cleaning—The PAGS process is designed to be cleaned in place.These processes are used routinely in the pharmaceutical and foodindustries where contamination can grow and make their productunsuitable for sale. This feature was integrated into the basic designby selecting the process equipment and interface connections for theitems actually contacting the microalgae growing media. Specialchemicals have been selected which perform these cleaning functions inthe above-mentioned industries. This feature will allow quick turnaroundand little or no component disassembly when microalgae species growthmust be altered by operators of the PAGS process.

Biofloc/fouling control. The turbulent flow of the light reactor chamberhas the added advantage of preventing the formation of biofilms andbiofloc within the modular light reactors. This reduces the laborrequired to clean the system, prevents attenuation of the light passinginto the light reactors (due to shading by adherent biomass), and lowersthe risk of colonization of the adherent biomass with bacterialcontaminants. An alternative approach can be used to deal with verysticky algal cultures. Due to the strong turbulent flow of the systemthe inclusion of plastic beads in the medium will provide additionalphysical mechanism to increase the self-cleaning capacity of the system.The beads are actually spherical bodies made of plastic about the samespecific gravity of water. The turbulence will “bounce” these “balls”along the tubular walls thereby keeping them clean and enhance thepassage of the required light.

Latitude Applicability—Current microalgae growing systems use naturalsunlight and warmth to grow the algae, therefore, they are competitivelargely in the tropics and subtropics where light and heat are readilyavailable.

There are many candidate applications where the winters are extreme andmicroalgae cannot be grown outside during that period. Suchopportunities could be abundant raw material availability or physicalneeds where an algae product should be grown in cold regions. The PAGSsystem can be easily grown indoors with synthetic and/or selected wavelength light sources. Current light emitting diode (LED) technologyallows a specific wave length of light to be generated via a veryefficient energy conversion process. Commercial sources of these readilyavailable. The invention allows indoor growth and temperature regulationsuch that no location is off limits.

Selective Species Growth Nature grows a “family” of living things in aspecific environment. This affords natural protection from predators andinsures survival of the species by allowing the strongest to survive.When we grow crops with only one plant or animal present we offer avirtual feeding ground for specific predators. The PAGS algae growingsystem offers a “closed environment” where outside influences arevirtually nonexistent. Materials such as food, diluents, or carriermedia are carefully screened and cleaned to an almost totally sterilecondition. This brings an Eden like growth condition for specific algaespecies. Conditions such as food concentration, temperature and chemicalconditions (acid or base condition) are all optimized for the intendedgrowth of a specific species.

Operation Function—During routine operation the media flows through theactual polymeric photobioreactors. The flow rates are high enough toprevent the algae from adhering to the photobioreactor wall; therebyblocking the required light admission. This feature is similar to thedesign of sewers where a “scour velocity” is designed in to prevent sandor other solids deposition interfering with the water flow. This highvelocity media is permitted because of the tensile strength of thepolymeric material and its minimization of U-turns which representalmost all the required pressure loss to maintain high flow rates.

The actual latitude (climate conditions) for the installation.Installations far removed from the equator may require artificial lightsources of specific wave lengths for optimal growing conditions. Thesubsystems described in the aforementioned schematics are composed ofcommercially available components widely used in industrialapplications.

Mixing—Present commercial microalgae growth systems are largely openponds or raceways that have paddle wheels to stimulate circulation andmixing of the growth media. These raceways are often large and mixing inthe actual media is poor. This manifests itself as the actual growingzone is a very thin “layer” near the actual surface. Mixing is verylimited which does not allow those microalgae near the bottom to receivethe sunlight necessary to prosper and multiply.

PAGS grows microalgae in circular polymeric “tubes” which are inconstant circulation. The circulation is done in fully turbulent flowwith a Reynold's Number in excess of 10,000. This allows all microalgaepresent to spend sufficient time in the growing zone to produce improvedoverall growth rates. Also the system maximizes the time spent in themodular light reactors with minimal time in the surge volumes wherenutrients and feed gases are introduced.

The PAGS polymeric tubes were developed in cooperation with a majorchemical company and the material offers very good light transmission.as well as superior overall resistance to the ultraviolet spectra ofsunlight which degrades most polymeric material quickly.

The PAGS polymeric tubes were developed in an exclusive cooperativeproject with Nu Methods Plastics Inc. The material has superior lighttransmissivity, tensile strength and high ultraviolet light resistancewhich make it suitable for outdoor tropic latitude application lastingseveral years. The material is also resistant to the seldom usedchemical cleaning protocol and can be repaired in place if smallpunctures or other “operational accidents” occur. The material's tensilestrength affords a safety factor of >4 for normal operations includingramped up pressure during system cleaning mode.

Turbulence—Turbulence is integral to the novelty of the PAGS design andhelps to provide the system with optimal properties beneficial to theproduction of algal biomass. Carefully controlled turbulence in theoptimal. zone for algae growth is important because of many factors.Importantly it increases the region within the system that is capable ofsupporting optimal photosynthesis thereby stimulating growth andreproduction of the algal cells. As the algal culture becomes denser theimportance of mixing becomes higher due to the “self-shading”phenomenon.

More elaborate techniques have been used to deliver non-limiting lightto algal cultures such as reduction of the light path length to a fewcentimeters (U.S. Pat. No. 5,104,803) or introduction of stacked lightguides (Jung et al., 2014). However, for most algae exposure to lightconstantly is not necessary and rapid mixing such that they are exposedas the correct interval will provide optimal photosynthesis. That if thecells are exposed directly to maximal insolation they will often besaturated and undergo a process known as photoinhibition—where the cellsdissipate excess light energy as heat and, in extreme cases, degradeportions of the photosynthetic apparatus to protect the cells.

When turbulent flow is used, cells are exposed to maximal lightintensity for only a short period and then returned to the culturewithout damage and replaced with other cells. Exposure in this wayallows the best use of incoming radiation so that cells absorb and useall the incoming light but photosynthesis is not saturated or damaged byphotoinhibition. This process has to be optimized for the algal speciesbeing used, as some are able to function optimally with exposure every 5seconds while others need light exposure every 30 seconds. Tuning thesystem for the organism is essential to the best yields.

Alternative carbon source—When cells are no longer provided sunlightgrowth ceases and respiration is the dominant metabolic reaction. Thismanifests itself as a sudden spike in pH which is detrimental to thealgae itself as well as a decrease or pause in biomass accumulation. ThePAGS system can prevent this spike via gas/material introduction and canbe modified to provide a fixed carbon source (e.g., sugars and sugaralcohols such as sucrose, glucose, or glycerol) to drive mixotrophicalgae growth during the dark periods of the day.

Many microalgae growing systems offer potential use in the mixotrophicmode. This means photosynthesis during daylight hours and some simplecarbohydrate food source at night. The PAGS process is uniquely suitedto this type operational mode because of the high degree of homogeneityand almost instantaneous response time to process condition changes.This would:

-   -   Minimize process condition secondary impacts (high pH spike)        such as when changing growth modes or feed stocks.    -   Drastically increase biomass growth because of longer growth        periods (no night time shutdown) and higher food conversion        rates when using carbohydrates as feedstock.    -   Allow optimal harvest of the grown microalgae by keeping the        algal cell density in the proper range during the entire        operational day.

Comparison of PAGS to production of algae in a conventional racewaysystem—One possible scenario for running the FAGS system is provided asa schematic in FIG. 2 and a same scale system using a conventionalraceway production system is diagramed in FIG. 3

The mass flows of each system have been modeled at the same scale andthe information is provided as Table 2.

The PAGS set up is designed with 10 light reactor tubes and the racewaysystem is modeled as 15×7 meters long with 3 meters wide sides of theraceways. Both are scaled to deliver 3,925 grams of biomass per day.From the modeled systems the outputs were modeled and are presented inTables 2 and 3. Critical differences in the process are seen in both thetypes of input and output streams as well as the magnitude of thosestreams. The PAGS system is much more efficient in incorporation of theadded carbon dioxide. It uses 5% of the carbon dioxide to produce thesame biomass quantities due to the enclosed design and recycle and reusedesign of the mixing and recycling chamber as well as the pressurizedsystem and delivery with the nanobubbler. The PAGS system also is muchmore efficient in conservation of the water supplied using 350 kg perday compared to greater than 10,000 kg/day lost in the raceway systemmainly to evaporative loss and dewatering a lower density culture.

TABLE 2 Model of PAGS process for production of 3,925 grams of drybiomass per day output system. Stream Type August Num- (Gas/ Temp Streamber kg/day Liq) C. Process Water 1 350 L 25 water all CO₂ 2 15 G 20 pureCO₂ Micro- 3 5 L 25 water 98% Nutrients Nitrogen 1.8% Phosphorus 0.2%Algae Seed 4 0 L 25 None Stock Nitrogen Gas 5 4,000 G 20 All HeatTransfer 6 110,000 L 35 propylene glycol/ Liquid water (50/50 .v/v)Dewatering 7 72 L 28 Removal Gas vented to 8 4,340 G 27 atmosphere HeatTransfer 9 110,000 L 32 propylene glycol/ Liquid water (50/50 v/v) AlgaeProduct 10 20 L 25 water 90% algae 10%

TABLE 3 Model of raceway process for production of 3,925 grams of drybiomass per day output system (21 raceways included in the model).Stream Type August Num- (Gas/ Temp Stream ber Kg/day Liq) C. ProcessWater 1 8,916 L 25 100% water Carbon dioxide 2 300 G 25 100% CO₂ Micro-3 120 L 25 98% water, 1.8% Nutrients Algae Seed 4 160 L 25 99.5% water,Stock 0.5% algae Cleaning Media 5 8,000 L 25 98% water, 2% saltsEvaporative 6 1,300 G 30 100% water losses Algae dewatering 7 8,000 L 3299.5% water, 0.5% algae Cleaning Waste 8 8,000 L 30 98% water, 2% saltsCarbon dioxide 9 85 G 30 Air with <1% lost CO₂ O₂ Production 10 11 G 30Air with <1% additional

MODES FOR CARRYING OUT THE INVENTION AND INDUSTRIAL

APPLICABILITY—Using a variety of methods exemplary embodiments of theinvention are directed at improving the growth of microalgae. This isparticularly applicable to reduction in the loss of water and CO₂ fromthe production system (see Table 2 compared to Table 3 which comparePAGS to a raceway production system).

The PAGS system is uniquely designed for clean production of algalbiomass. Therefore, one of the modes of production is to produce asingle alga that is not a rapid grower but produces a useful bioproduct.Such an organism could not compete in open pond systems and the uniquedesign of the PAGS system provides a better culture condition thanexisting photobioreactors. Such high value products could be secondarymetabolites, nutritional oils (e.g. docosahexaenoic acid, arachidonicacid, eicosapentaenoic acid, and other long chain polyunsaturatedacids), carotenoids (e.g., astaxanthin, beta-carotene, canthaxanthin,and other unique carotenoids), phycobiliproteins (e.g. allophycocyanin,phyocyanin, and phycoerythrin), polysaccharides (fucomannans,glucomannans, and the like) and other high value compounds. Due to thetightly controlled design of PAGS these could be used as food gradematerials fat high value applications.

The PAGS system could also be used as an enclosed production system forscaled up growth of genetically manipulated microalgae. Transgenictechniques have the capacity to greatly enhance the productivity ofphotosynthesis in microalgae, however the fear that unintended releaseof these organisms could endanger the environment hinders their use inmost algal production systems. The design of PAGS could allow containedand controlled growth of such organisms under conditions whereregulatory approval is possible and safety can be assured.

The PAGS system could also be used to scrub undesirable pollutants fromeither aqueous waste streams or vapor emissions. Many industrialprocesses produce wastewaters that are high in materials useful foralgal growth (such as nitrogen compounds, phosphates, and othermicronutrients) that could be utilized in the PAGS system to effectivelyscrub these nutrients and produce c-lean water. Similar approaches havebeen used with algae and wastewater in the literature (Perez et al.,2015). Likewise, industrial gas sources produce carbon dioxide andnitrogen and phosphorus compounds that can be effectively converted toalgal biomass. While the use of industrial waste mostly precludes theuse of the biomass for food and feed applications, purified bioproductscan be made for renewable chemical production. Alternatively, thisbiomass can be used as a biofertilizer for fields or as a feedstock forbiofuel production.

Alternative Feed Materials for the PAGS Algae Growing Plant

The PAGS process has been designed as a robust, industrial facility.There is considerable tolerance in the feedstocks that can be introducedand converted into algae biomass. Some of the candidate items are shownin Table 4 and FIG. 9. Table 4 offers the amount of Carbon Dioxide thatis potentially available from 4 commodity product systems. The amount ofCO₂ involved in each of these processes is significant and the unitsdisplayed are in millions of metric tons per year.

TABLE 4 Industrial processes producing suitable feed gas for the PAGSprocess. Total Product CO₂ Output PAGS Content Worldwide ProductionProcess/ of Gas (millions of CO₂/ (10⁶ Product (mole %) metric tonnes)Product tonnes/year) Direct Reduced 25 (1) 100 0.8 23 Iron (MidrexProcess) Ethanol (US 95   50 0.9 13 only) Cement 40 (1) 3,500 0.9 900Aluminum A 70 (2) 3 10.5 0.4 Note 1 - Solids removal required before useNote 2 - CO removal or conversion required before use

The PAGS process could utilize each of the candidate gas streams in theconcentrations expected from the parent process operation. The expectedpenalties for using these materials are:

a. Slight loss of utilization in the feedstock carbon dioxide.

b. Slight increase in the size of the nanobubbler that would be used.

c. Slight increase in the amount of vapor off gas that would need to behandled.

Many of these industrial processes use natural gas as the starting orrequired component feedstock. Many of these also are located in aridregions where water is either expensive or in very short supply. ThePAGS system needs only a small percentage of process water thatcompeting algae growing systems require. This feature is explained inearlier portions of this document.

One other unique benefit of the PAGS process is that algae could begrown in a true mixotrophic mode. This means that simple carbohydratescould be used during the non-daylight hours and biomass production wouldincrease accordingly. The only additional system required would be asimple agitated holding tank and pump to introduce the carbohydrate intothe existing surge tank. This system is shown in summary form in FIG. 12and would add less than 20 to the capital cost of a standard PAGS unit.The features of the PAGS system of high turnover, efficient mixing, etc.would all positively affect the mixotrophic mode as well.

Other Mode of Operation of PAGS.

The PAGS process is very robust and flexible. With this as a tool one isable to take advantage of the many processes and traits that micro algaeemploy in their inherent makeup. For convenience we have organized theseapplications into areas which appear attractive because of upcomingpolitical events or trends that would make these applicationsattractive. These general classes of applications include: MetalsRecovery from Interim Processes and Waste Streams, CO₂ Sequestrationfrom large Industrial Point Sources, Valuable Materials that are now orcan be produced by Micro Algae and Waste Water Treatment SystemAugmentation.

Metals Recovery from Interim Process and Waste Streams

Recovery of uranium from native phosphate ores. It is widely known thaturanium occurs in all phosphate rock deposits. These uraniumconcentrations range between 50 and 200 parts per million in the oredeposit. A typical phosphate rock processing operation (normallyphosphoric acid is the wanted product) would handle, even at today'sdepressed uranium prices somewhere in the range of $50,000,000 ofuranium per year. The overall uranium in phosphate rock is in excess ofthe current known world reserves. Certain species of algae have anaffinity for metal ions, particularly if they exist in the +2 valencestate. The wet process for making phosphoric acid involves leaching ofthe rock with strong mineral acid and the uranium is found in solutionas UO²⁺⁺ (known as uranyl ions). This state or condition of the uraniumwould favor the adsorption of the uranyl ion by micro algae on theirpolysaccharide outer layers. Preliminary testing would indicate that thealgae could “hold” as much as 500% of their own dry weight for somethingwith the atomic weight of uranium. Using the above information, atypical phosphate rock processing operation could utilize a few millionpounds of microalgae per year to recover the majority of this now wastedresource. Required modifications to the PAGS process are very minor forthis application as the algae could be used in a relatively dilute (1-10grams per liter) concentration and the algae need not be alive for theadsorption process to occur. Final conversion the adsorbed uranium tothe current market composition (U₃O₈ or yellow cake) could be a plasmatorch system which is currently available and used for waste disposaland metal recovery processes.

Recovery of Rare Earth elements. Rare Earth elements are the lanthanides(atomic number 57 through 71) and are relatively common in the earth'scrust. Most are more common than element iodine which is used as ahousehold antiseptic. They are receiving interest because of their usein the semiconductor industry, powerful magnets, communication devicesand etc. The major commercial source today is China because theirextraction and purification produces toxic waste streams and byproducts. Rare Earth elements exist in the coal found in the AppalachianMountains. They are also candidates for microalgae adsorption andrecovery and the PAGS process could be used here in conjunction with afacility that pulverized coal. Pulverized coal would be an easycandidate for mineral acid leaching that would convert the Rare Earthmetals to a positive ion. The concentration required for the microalgaeis relatively low an as above, the algae need not be alive to performthis function. It is an adsorption process where the metal ion adheresto the “sticky” polysaccharide coating of the algae. Political eventsmay require that a source other than China is needed for these highvalue materials and a modification to the PAGS process could be used atan existing facility that currently ignores the Rare Earth materialspresent in the coal which is combusted as fuel.

Recovery of Radioactive Nuclides. These are normally products of thefission process used for electrical power generation from nuclearreactors. Typically, they are isotopes of elements that have a half-lifeof 1-10,000 years and are cancer causing in most mammals, includinghumans. In the case of the Fukushima disaster in Japan some 100,000,000tonnes of water containing isotopes of cesium, strontium and plutoniumwere created. The concentrations of these materials in the water arequite low but beyond the safe limits for simple disposal. Algae could beused to capture these materials by providing a volume where the algaeconcentration is quite high (perhaps 10,000,000 cells per mL) and theadsorption process would bioaccumulate these materials. The radioactivematerials still exist but in a much smaller volume that could becontained for the periods required. A PAGS facility proximate to thedisaster site could function for a period of time required to processthe contaminated water (perhaps 1-2 years). The problem still remainsregarding the ultimate fate of the materials but the volumes involvedare much more manageable.

CO₂ Sequestration from Large Industrial Point Sources

Carbon Dioxide is likely to receive more attention if the planetcontinues to warm with the attendant problems caused by the greenhousegas. A likely target for reducing the emissions will be large industrialfacilities that produce a high concentration of CO₂ in their effluentgas. This high concentration would be attractive as a feed stock for aPAGS facility. This wastestream (which could become a cost for theproducer) would be ideal feed stock for growing algae and likely couldbe obtained at zero or perhaps even negative costs. Candidate processesthat currently fit these criteria are listed in Table 4 with estimatedworld effluent values.

The PAGS system would capture 90%+ of the CO₂ and convert it intobiomass which at a typical industrial installation would result in acommodity type material that could be sold for various uses.

Valuable Materials that are Now or can be Produced by Micro Algae

This class of materials can largely be described as niche or high valueitems that function as nutraceuticals, active pharmaceuticalingredients, cosmetic components or other high value items. Typically,these materials (the active ingredient) have retail selling prices of$10,000-$100,000 per kilogram. Many of these items are known to exist insmall concentrations for specific micro algae species. The problem todate is being able to obtain these microalgae species in the puritylevels needed for component extraction and further processing.Typically, the worldwide market for these materials is quite small;somewhere between 1-100 tons per year. As an example one material couldbe a tocopherol like material. Tocopherol (or vitamin E) is a complexmolecule with 4 asymmetric carbon sites. This would yield as many as 16optical isomers and perhaps 8 have been studied in some detail.Tocopherol can be made synthetically but the isomers found differ fromthe natural material which may start in soybeans. This confirms out thatNature's laboratory operates differently than ours and the materialsproduced naturally could be different and have higher values or sellingprices. This is true for the many products that ‘could be obtained frommicroalgae and these would be quantified once a reliable quantity ofspecific microalgae could be obtained at a predictable cost. PAGS isdesigned to satisfy such criteria.

Waste Water Treatment System Augmentation

Waste Water Nutrient Removal. Microalgae need both phosphorus andnitrogen to maintain their growth and reproduction cycle. Currently thenitrogen and phosphorus have been identified as being largelyresponsible for the Chesapeake Bay's reduction in crustaceans, shellfishand sport fish populations. It has been demonstrated that micro algaecan be used to reduce the concentration of nitrogen and phosphorus downto very low levels. The process required converting a portion of theexisting wastewater stabilization ponds into volumes of very high algaeconcentration. This was done by using a PAGS type algae growing systemand a cross flow filtration system which concentrated the algae andproduced a very clean permeate. This permeate was suitable for releaseinto the Pacific Ocean or almost any other water body. The FAGS processneeded no modification except the expansion in capacity of thedewatering system. In this instance, the permeate from the dewateringsystem was the industrial facility's waste water stream. The PAGSprocess provided robust healthy algae that acted as a continual seedstock while most of the nitrogen and phosphorus assimilation was done byalgae recycled from the growing volumes. Surplus algae (you do not needto recycle the total produced) can be converted to various saleable byproducts.

Fracking Water Cleanup.

The water employed in the fracking process will contain many heavymetals and materials that are not suitable for release into local riversand estuaries. Microalgae will have a place in the concentration andcollection of these as yet undefined materials. Typically, it takesseveral years for the regulatory statutes to respond to new materialsthat appear in waste streams. The PAGS process will likely haveapplication here as a solution to an ongoing waste treatment problem.

EXAMPLES

Certain embodiments of the invention will not be described in moredetail through the following examples. The examples are intended solelyto aid in more fully describing selected embodiments of the invention,and should not be considered to limit the scope of the invention in anyway.

Example 1—One Set Up and Operation Mode of the Photosynthetic AlgalGrowth System (PAGS) of the Current Invention

The PAGS microalgae growing system as diagramed in FIG. 1 has thefollowing capabilities:

-   -   a. The system is closed to the outside environment preventing        intrusion by predators and other alien bodies.    -   b. The system is also under positive pressure to ensure the        system “leaks out” similar to the production of active        pharmaceutical ingredients. The starting materials are known and        free from unwanted items that cause contamination.    -   c. The system is expandable and economies of scale can be        realized. This means large central utility systems and        supporting functions. The actual growing system is modular and        expandable based on specific customer requirements.    -   d. The system is robust and can function on a 24/7 basis.        Typically, this would mean microalgae growing in the day and        harvest at night. Capital costs for the required ancillary        processing equipment dictate high utilization factors.    -   e. The system is designed with an eye to total operation. This        means consideration of the transients (start up and shut down).        Operating mode, in-Situ repair during operation and tolerance of        catastrophic events (major failure or operator error).    -   f. The system provides optimum microalgae growing conditions.        These will be influenced by the diurnal cycle through ambient        temperature, light concentration and nutrient needs.

The above items are discussed in more detail below:

Closed System—The system is essentially air tight and the known (ordesigned) leakage points will be maintained and monitored. In our systemthis feature will be provided by a sterile nitrogen blanket thatoperates continuously.

Starting Materials—All the starting (raw) materials are of known andapproved constituents. This includes the process water, recycle water,algae seed stock, micronutrients and the nitrogen blanket gas. Thiswould permit utilizing such capital cost saving features as cast ironpumps (with purified process water as the sealing material) and similarstandard or commodity items.

Economies of Scale—The system shares utilities and support functionswith other algae growing modules. An algae growing module (as presentlyenvisioned consists of 10 100-meter long polymeric plastic tubes of 100mm diameter. Additional modules could be added as customer requirementsdictate. Also extending the tube lengths up to a factor of 10 arepossible if required for production.

Robustness—The system operates with some margin of safety. The requiredlight transmission, tensile strength and extrudable characteristics ofthe plastic chosen for construction. Early experimental work hasconcluded that polyurethanes have the best blend of characteristics forthe actual tubes. The diameter of the microalgae growing tube is about100 mm. This would seem to best utilize the available light conversionto biomass. These functional criteria include:

-   -   i. Extrudable Material (long runs with minimal connections)    -   ii. High Tensile Strength (see FIG. 5)    -   iii. High Light Transmissivity (>90%)    -   iv. High ultraviolet light tolerance (resists yellowing and        strength loss)    -   v. Customizing Capability (flexibility enhanced with polyol        selection etc.)    -   vi. Limited for toxic additives (phthalates etc.)

Total Operation—The system is designed for total operation.Considerations include:

-   -   i. Start Up—A small volume is required which can be expanded        incrementally (by opening valves) maintaining good algae        concentration for growth.    -   ii. Operation—Growing during the day, harvest at night, the        surge tank volume merely reduces maintaining algae concentration        promoting consistent dewatering/concentrating activities.    -   iii. Day/Night Operation—Once day light is no longer available,        the oxygen product may cause the pH in the system to rise        suppressing later (the next day) growth. Nitrogen is sparged in        the surge tank and oxygen is removed as it is generated, thereby        increasing growth rate. This eliminates slow growth start up the        next day.    -   iv. Cleaning/Species Change—The system is designed for in situ        cleaning (by chemicals) and free draining. Flows can be        increased to allow scouring of the system and minimal residual        contamination.    -   v. Optimal Growth Conditions—The system is designed to control        temperature and process conditions. The temperature is        controlled by:    -   vi. Cooling (nitrogen sparge and subsequent water evaporation)    -   vii. Heating (polypropylene glycol/water in tank jacket)

It should be noted that every algal species likely has optimal processconditions and nutrients and other additives can be introduced asneeded.

Process Water System

The process water system is the heart of the microalgae growing systemand diagramed in FIG. 7. It prevents contamination of the system bypresenting a water of known cleanliness to contact the algae. This isdone using a water filter system followed by an ultraviolet lightsterilizer. Typically, the filtration system includes the following:

-   -   a. A coarse filter with a maximum particle flow permission limit        of no more than 5 microns;    -   b. An activated charcoal filter to remove any organic material        or halogen ion that might exist in either the source water or        the recycled water from subsequent operations;    -   c. A fine filter with a maximum particle flow permission limit        of no more than 0.35 microns;    -   d. An ultraviolet light sterilizer to destroy any spores or        bacteria that might get through the filtration system. The        sterilizer has a minimum exposure capability of exposing the        water to 30 watts per gallon per minute to ensure sterility.

The system operates continuously and is installed in a duplex mode(installed back up). This is analogous to a boiler operation whichnearly always has two source pumps to ensure the boiler has 24/7capability. The filters have bypass capability which allows thecartridges to be exchanged while the system is operating.

Any “new or recycled” water which is introduced to the system must firstgo through the above process before reaching the surge tank whichprovides a clean ample water source for the process.

Nitrogen System—The nitrogen system has two major functions and isdiagramed in FIG. 8. It provides a sterile blanket under positivepressure to the entire microalgae growing system and provide coolingcapability by the evaporation of water by the sparging operation in themicroalgae growing surge tank. During the sparging operation the productoxygen is also removed which speeds up the overall photosynthesisprocess. The nitrogen would likely be stored at a proximate tank wherethe nitrogen is likely liquid. This material would have been producedvia a cryogenic distillation process and would be very pure and sterile.As backup a sterile filter would be included before the nitrogen isintroduced to the microalgae growing process. The sterile filter wouldbe provided in a duplex mode (an installed spare) to ensure that all thenitrogen gas is of suitable quality for the growing process. Similarcare would be taken if ambient air is used.

Gaseous CO₂ Feed System—CO₂ is the normal food for microalgae. This CO₂(in nature) is present in the ambient air at a concentration of about400 parts per million. The CO₂ is soluble in water and dissolvesfollowing the principles outlined in Henry's Law. Therefore, the growthrate of the microalgae is dictated by the mass transfer rate of CO₂ fromambient air into the water where it is dissolved and the microalgaeassimilate this into resulting biomass.

The PAGS process intends to make the rate limiting step the actualability of the microalgae to assimilate the CO₂. Therefore, ample CO₂must be present in a dissolved form.

The mechanism for this involves:

-   -   a. —Introducing the pure (or nearly so) CO₂ as very fine/small        bubbles which have an extremely high surface area to contained        volume ratio (units of inverse length). We have chosen to adapt        a novel nanobubble generator for this purpose (see FIG. 9).    -   b. —Operating the system at much higher than ambient pressure;        higher pressure increases the CO₂ dissolving rate as well as        increasing the amount of CO₂ the water will accept.

Many existing microalgae growing systems use a mixture of air and CO₂ asa feed material. The rationale behind this is to mimic the low level ofCO₂ (400 ppm) which nature uses. The down side of this is the companionair with the CO₂ actually strips some wanted material out. This processis common if you want to remove oxygen from a liquid stream; just bubblea surplus of nitrogen through it. PAGS uses a high content CO₂ gas andforces the limiting step to be the actual assimilation process (or thereaction kinetics). Almost all existing industrial processes are limitedby either mass or heat transfer system capability. This feature willimprove our unit volume productivity and overall yield.

The CO₂ used in any microalgae growing process must be free of heavymetals or other contaminants that could be toxic to the actual algae orthe downstream products that may be created. Therefore (depending on theactual source) the characteristics of the CO₂ must be known fully and bereliable.

Dewatering System

Microalgae will be grown in the PAGS operation at a concentration ofabout 0.5 grams of biomass per liter of water or media. Most customerswill desire this biomass to contain much less water than the aboveamount. Hence our “standard” system will have the capability toconcentrate the biomass by a factor of 20 which will yield a “thick”paste like material which is still transferable by standard pumps andnot significantly damage or degrade the biomass. Our standard system isa cross flow filtration operation (FIG. 10) which has the followingadvantages:

There is no “dead end” step where a filter cake accumulates and must beperiodically removed (normally by hand and is a tedious job).

The permeate (removed water) is almost totally free of suspended solids.This is recycled to our source water treatment system for reuse. Therecycled water also carries valuable concentrations of dissolvednutrients which are recycled and converted into biomass in lateroperation.

These crossflow filters were developed for the pharmaceutical industry(vaccine purification) and they are designed for small hydraulicdiameter body removal. These devices have been modified by others toaccept the industrial scale of operation.

Seed Stock and Nutrient Introduction System—The microalgae growingsystem will need initial seed stock and periodic infusion ofmicro-nutrients. These will be algae seed stock and nitrogen andphosphorus containing compounds. These materials will be produced andformulated off site and introduce via a metering pump into the surgetank of the microalgae growing system as shown in FIG. 11. Initially,the seed stock will be introduced with a relatively small “heel”(residual volume) in the tank to minimize the potential for overdilution. This over dilution would require additional time (and risk)for the algae to reach a healthy and reproductive state. The microalgaegrowing system is designed for step wise volume expansion such that theinitial inoculation volumes required are relatively small and the systemevolution can be controlled by valves which cause additional growingvolumes to become active.

The nutrients are nitrogen and phosphorus containing compounds andperhaps even various vitamin-like substances which may be required. Theywill be introduced via metering pumps and ongoing concentrations will becontinuously monitored. These materials will be available to the algaegrowing process such that optimum growth rates can be maintained. ThePAGS growing operation has very quick response times and turbulence isvery high which maintains consistent and uniform concentrations.

Example 2—Running PAGS Process as a Metals Recovery from InterimProcesses and Waste Streams

Metals Recovery from interim Processes and Waste Streams, the PAGSprocess functions to produce a sacrificial stream of microalgae which isintroduced to a highly acidic (low pH) stream. The contact time requiredhere is about 15 minutes and the concentration of algae needs to be inthe range of 5-50 million cells/mL (this is perhaps a solidsconcentration of 0.050.5 grams per liter) of process solution dependingon the hydraulic diameter of the specific algae used. The contact volumewould be operated as a simple continuously flow stirred tank reactor(CFSTR or backmix system) and the incoming algae would need to be at ahigher concentration than the required concentration in the reactor.

For an industrial application such as the phosphate rock uraniumrecovery system, the active volumes here would quite large, butefficient pulsed gas mixing or other alternatives could be used. Lightis not required for the algae so the physical dimensions of the volumeare not constrained. The PAGs system would be run as described inExample 1 but the outlet stream from this operation would need to befurther processed to remove the water and convert the final metalproduct (in this case uranyl ions) into the final commodity product U308or yellowcake; but this is independent of the PAGS process.

Example 3—Using the PAGS System for CO₂ Sequestration from Large PointSources

CO₂ Sequestration from large Point Sources would require the number ofPAGS modules to be quite large. This is because for a typical industrialfacility, such as a direct iron ore reduction facility, that may produceabout 1,000,000 tons of iron per year. The CO₂ produced here is about90% of the product by weight which yields an instantaneous rate of30,000 cubic feet per minute of CO₂ gas. This gas would be present atabout 28% by volume in the facility's effluent. For this application thePAGS system would be run as in Example 1 but requires the PAGSnanobubbler system to be upgraded to accept these volumes. Also if it isdesired that all the CO₂ be processed or converted an LED or otherartificial light system would need to be added to PAGS for operation innon-daylight hours. Also the PAGS dewatering system would need to beexpanded to accept the large volumes of algae media that would need tobe processed. The PAGS process is uniquely qualified for thisapplication because of:

-   -   i.—The nearly total recycle or capture of the water used    -   ii.—The efficient use of the required nutrients    -   iii.—The high utilization of the CO₂

These advantages are compared to existing competing alternatives and thefact that many of these facilities (like direct iron direct reduction)are located in arid regions where process water is expensive ornonexistent.

Example 4—Production of High Value Products Such as Astaxanthin in thePAGS System

Production of astaxanthin or other valuable materials already producedby microalgae (such as the phycobiliproteins or sporopolinin) are madein the PAGS system as described in Example 1. Essentially nomodifications are required in the PAGS facility other than to installdownstream processing for extraction of astaxanthin. This easy shift toproduction of valuable products already produced in microalgae is due tothe basis for design and other applications were included in the modularaddition concepts employed. This market could be quite large ascurrently many niche products are known to be contained in microalgae.They have not been developed because a reliable and economicallycompetitive process for producing the algae is currently not available.

Example 5—Waste Water Treatment System Augmentation Using PAGS

Waste Water Treatment System Augmentation is easily done using the PAGSsystem as described in Example 1 with the exception of the sourcing ofthe water used to make up the algal growth medium. The PAGS facilityproduces robust microalgae feed stock or seeds that act as the parentsto micro algae in a volume of the existing waste water treatment systemthat has a very high microalgae content. This high content of microalgaeallows them to scavenge the nitrogen and phosphorus (nutrients) in thewastewater to actually become part of the biomass. This is laterrecovered and converted to many potential economic uses. The requiredmodifications to the PAGS facility are:

-   -   a. A larger dewatering system as the clear permeate here        actually becomes the existing facility's treated wastewater        stream.    -   b. An additional gas handling system that could be used to mix        the volumes required for the actual assimilation of the nitrogen        and phosphorus values in the wastewater.    -   c. A water handling system that would be used to transport the        algae containing media from the existing modified waste water        treatment system to the dewatering operation.    -   d. No changes in the operation of the PAGS system are required.

Definitions

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention pertains. Although methods and materialssimilar or equivalent to those described herein can be used in thepractice or testing of the exemplary embodiments, suitable methods andmaterials are described below. All publications, patent applications,patents, and other references mentioned herein are incorporated byreference in their entirety. In case of conflict, the presentspecification, including definitions, will control. In addition, thematerials, methods, and examples are illustrative only and not intendedto be limiting.

“Microalgae” have been variously defined through the ages and it isprudent to describe the microalgae to which this invention could apply.For the purposes of this invention, microalgae include the traditionalgroups of algae described in Van Den Hoek et al. (1995). This inventioncan be used in the photosynthetic and mixotrophic culturing ofmicroalgae.

“Phototrophic” and “photoautotrophic” are used interchangeably and referto growth on simple medium without the use of fixed organic carbon, allcarbon is supplied by inorganic carbon (e.g., carbon dioxide,bicarbonate, or carbonate).

“Mixotrophic” growth is growth in the presence of a fixed carbon sourcein the light with inorganic carbon also present where improvedproductivity is achieved due to the presence of the fixed organiccarbon.

“Photobioreactor” is a system where a photosynthetic organism is capableof carrying out photosynthesis due to the design of the system (allowingexposure to light and control of conditions to allow cell growthamenable to photosynthesis.

“Light reaction chamber” is a section of a device where photosynthesisis allowed to proceed.

Reynold's Number” is a dimensionless ratio of the inertial energydivided by the viscous dissipation energy and it is now believed that avalue of 2100 would represent turbulent flow which has not beenrigorously defined by analytical techniques. Basically, you useexperimental data to define required system drops, etc.

The term “self-shading” refers to the reduction of light available tospecific algae cells due to the presence of other algae cells throughwhich the light must pass prior to hitting the algal cells of interest.As a population phenomenon, “self-shading” has the effect of limitingthe maximum potential culture cell density by restricting the lightavailable to the average cell in the culture. Often this is referred toas “self-limiting” or “light limited” cultures which, for the purposesof this application will be considered equivalent terms.

The microalgal growing system and its associated methods arecollectively and individually referred to herein as the “Pure AlgaeGrowth System” “PAGS” which are used interchangeably in thisapplication.

The pure algae growth system of the present invention is for feeding aplurality of input materials and for generating pure algae there from.The feeding of the input materials and the generating of the pure algaeis done in a safe, convenient, and economical manner. In the system ofthe present invention, first provided is a primary tank for receivingthe plurality of input materials, for mixing the plurality of inputmaterials, and for dispensing as output material the input materialsafter mixing. The primary tank has an upper extent with a top. Theprimary tank has a lower extent with a bottom. The upper extent is in acylindrical configuration with a vertically oriented upper axis. Thelower extent is in a geometric configuration with a vertically orientedlower axis coextensive with the upper axis. The plurality of inputmaterials includes an algae feed stock supply with an algae feed stockinput line coupling the algae feed stock supply to the top of theprimary tank. The plurality of input materials also includes amicro-nutrient supply with a micro-nutrient input line coupling themicro-nutrient supply to the top of the primary tank. The plurality ofinput materials also includes a cleaning solution supply with a cleaningsolution input line coupling the cleaning solution supply to the top ofthe primary tank.

Next provided is a sterile gas supply. A sterile gas supply input linecouples the sterile gas supply to the top of the primary tank.

Next, a heating/cooling fluid supply is provided. Heating/cooling fluidsupply input line couples the heating/cooling fluid supply to anintermediate extent of the primary tank and passes through the primarytank for temperature control purposes.

Next provided is a carbon dioxide supply. A carbon dioxide supply inputline couples the carbon dioxide supply to a primary location followingthe primary tank.

A raw water supply is next provided. A raw water supply input linecouples the raw water supply to a secondary location following theprimary tank.

Next, a plurality of output stations are provided. Included are a ventto atmosphere station, a heating/cooling media return station, acleaning disposal station, and an algae concentrate/product station.

The vent to atmosphere station includes a vent to atmosphere outputline. The vent to atmosphere output line couples the top of the primarytank to the vent to atmosphere station for disposing of gasses formed inthe top of the primary tank.

The heating/cooling media return station includes a heating/coolingmedia output line. The heating/cooling media couples the heating/coolingmedia input line to the heating/cooling return station for controllingthe temperature in the primary tank.

The cleaning solution disposal station includes a cleaning solutiondisposal output line. The cleaning solution disposal output line couplesthe bottom of the primary tank and the cleaning solution disposalstation. The cleaning solution disposal line includes a pump followed bya nano bubbler at the primary location followed by an algae growingsystem.

The algae concentrate/product station includes an algaeconcentrate/product line between the bottom of the primary tank and thealgae concentrate/product station. An algae dewatering system isprovided in the algae concentrate/product line. A water return linecouples the algae dewatering system and a water treatment system at thesecondary location.

Next provided in the system is at least one first tube with anassociated return second tube. The at least one first tube and thereturn second tube are transparent for the visible treatment of algaepassing there through.

The nano bubbler and the algae growing system and the algae dewateringsystem constitute a module. The system includes at least one module.

Lastly provided in the system is a solid weigh system and feederoperatively coupled between the micro-nutrients supply and the primarytank.

The flow of material through the algae growing system is turbulent witha Reynolds Number of 10,000, plus or minus 20 percent.

The present invention includes a pure algae growth method for feeding aplurality of input materials a d for generating pure algae there from.The feeding of the input materials and the generating of the pure algaeare done in a safe, convenient, and economical manner. The methodincludes the following steps.

The first step is providing a primary tank for receiving the pluralityof input materials, for mixing the plurality of input materials, and fordispensing as output material the input materials after mixing. Theprimary tank has an upper extent with a top. The primary tank has alower extent with a bottom. The upper extent is in a cylindricalconfiguration with a vertically oriented upper axis. The lower extent isin a geometric configuration with a vertically oriented lower axiscoextensive with the upper axis.

The next step is providing the plurality of input materials including analgae feed stock supply with an algae feed stock input line coupling thealgae feed stock supply to the top of the primary tank. The plurality ofinput materials includes a micro-nutrient supply with a micro-nutrientinput line coupling the micro-nutrient supply to the top of the primarytank. The plurality of input materials includes a cleaning solutionsupply with a cleaning solution input line coupling the cleaningsolution supply to the top of the primary tank.

The next step is providing a sterile gas supply with a sterile gassupply input line coupling the sterile gas supply to the top of theprimary tank.

The next step is providing a heating/cooling fluid supply with aheating/cooling fluid supply input line coupling the heating/coolingfluid supply to an intermediate extent of the primary tank and passingthrough the primary tank for temperature control purposes.

The next step is providing a carbon dioxide supply with a carbon dioxidesupply input line coupling the carbon dioxide supply to a primarylocation following the primary tank.

The next step is providing raw water supply with a raw water supplyinput line coupling the raw water supply to a secondary locationfollowing the primary tank.

The next step is feeding the plurality of input material to the primarytank.

The next step is providing a plurality of output stations including avent to atmosphere station, a heating/cooling media return station, acleaning disposal station, and an algae concentrate/product station.

The next step is including in the vent to atmosphere station a vent toatmosphere output line coupling the top of the primary to the vent toatmosphere station for disposing of gasses formed in the top of theprimary tank.

The next step is including in the heating/cooling media return station aheating/cooling media output line coupling the heating/cooling mediainput line to the heating/cooling return station for controlling thetemperature in the primary tank.

The next step is including in the cleaning solution disposal station acleaning solution disposal output line coupling the bottom of theprimary tank and the cleaning solution disposal station, the cleaningsolution disposal line including a pump followed by a nano bubbler atthe primary location followed by an algae growing system.

The next step is including in the algae concentrate/product station analgae concentrate/product line between the bottom of the primary tankand the algae concentrate/product station, an algae dewatering system inthe algae concentrate/product line, water return line coupling the algaedewatering system and a water treatment system at the second location.

The final step is feeding the output stations from the primary tank.

Alternatively, the method includes the step of feeding algae feed stockto the tank in the absence of a sugar solution to achieve phototropicalgae growth.

Also, alternatively, the method includes the step of feeding a sugarsolution to the primary tank in the absence of algae feed stock andvisible radiation to achieve photographic algae growth.

For operating the system in non-daylight hours, the carbon dioxidesource is removed and replaced by a feed to the tank of sugar,preferably an aqueous solution.

As to the manner of usage and operation of the present invention, thesame should be apparent from the above description. Accordingly, nofurther discussion relating to the manner of usage and operation will beprovided.

With respect to the above description then, it is to be realized thatthe optimum dimensional relationships for the parts of the invention, toinclude variations in size, materials, shape, form, function and mannerof operation, assembly and use, are deemed readily apparent and obviousto one skilled in the art, and all equivalent relationships to thoseillustrated in the drawings and described in the specification areintended to be encompassed by the present invention.

Therefore, the foregoing is considered as illustrative only of theprinciples of the invention. Further, since numerous modifications andchanges will readily occur to those skilled in the art, it is notdesired to limit the invention to the exact construction and operationshown and described, and accordingly, all suitable modifications andequivalents may be resorted to, falling within the scope of theinvention.

That which is claimed is:
 1. A continuous growth system for inclusionand/or growth of algae with an in-situ cleaning functionality, thesystem comprising: (a) a central distribution tank comprising atemperature controlling jacket and acting as a central process controllocation, wherein growth and process variables are controlled,micronutrients nitrogen and phosphorus are supplied, sterilized inertgas acts as a blanket to block intruding species, and sterilized water,CO₂ and a cleaning solution are supplied; (b) a computer systemcommunicatively connected to the central distribution tank formonitoring the process variables and for modulating them to maintaingrowing conditions and subsequent cleaning of the growth system; (c) aplurality of microalgae growing tubular modules communicativelyconnected to the central distribution tank and positioned for exposureto a light source, wherein the microalgae growing tubular modules arefabricated of a translucent or transparent polyurethrane polymerresistant to ultraviolet degradation and fabricated in continuouslengths of about 100 meters, wherein the microalgae rowing tubularmodules have a diameter for maintaining tensile strength, movement of aspecific volume of microalgal culture and light exposure; (d) apressurized pumping source connected to the central distribution tankfor pressurizing the growth system, wherein the internal pressure of thegrowing system is at a pressure sufficient to cause a turbulent flowwithin the growing system and minimize the accumulation of biofilms inthe microalgae growing tubular modules; (e) a nano-bubbler positionedbetween the pressurized pumping source and microalgae growing tubularmodules thereby providing and producing bubbles of CO₂ for increasedsolubility of CO₂ in the growing system; (f) an inline dewatering systemcomprising a filtration system which allows algae harvesting while thegrowing system is functioning, thereby maintaining algae growingconcentrations in the growing system; (g) a temperature adjusting systemcommunicatively connected to the jacketed central distribution tank tomaintain a growth temperature in the growth system; (h) a venting systemattached to the central distribution tank to remove unwanted gassesformed in the growth system; and (i) an inline cleaning and recoveringsystem for capturing unused reactants and process water, and introducinga cleaning solution into the central distribution tank withoutdisassembly and reassembly of the growth system to provide a cleangrowth system for reinoculating the growth system with the previousalgae, introducing one or more different algae species or introducing anew waste type stream.
 2. The continuous growth system of claim 1,wherein the continuous growth system functions in a mixotrophic mannerand provides a 24/7 growth cycle.
 3. The continuous growth system ofclaim 1, wherein the microalgae growing tubular modules have a diameterof about 100 millimeters.
 4. The continuous growth system of claim 1,wherein the continuous growth system further comprises an inlet forintroducing an aqueous sugar solution for growth during non-daylighthours.
 5. The continuous growth system of claim 1, wherein the turbulentflow causes a scouring effect on the internal surfaces of the continuousgrowth system, thereby minimizing accumulation of a biofilm and blockingof required light.
 6. The continuous growth system of claim 1, whereinthe applied pressure ensures that any transfer of materials or gases isout of the continuous growth system, thereby reducing the chance ofcontamination.
 7. The continuous growth system of claim 1, wherein thetemperature is maintained by introducing a mixture of water andpolypropylene into the temperature controlling jacket of the centraldistribution tank.
 8. The continuous growth system of claim 1, whereinthe translucent or transparent microalgae growing tubular modules andturbulent flow allow the microalgae to spend sufficient exposure time inthe light source.
 9. The continuous growth system of claim 1, whereinthe turbulent flow within the continuous growth system has a flow rategreater than a Reynolds Number of 10,000.
 10. The continuous growthsystem of claim 1, wherein the internal pressure in the continuousgrowth system is about 2 Bars.
 11. The continuous growth system of claim1, wherein the number of microalagae-growing tubular modules is
 10. 12.The continuous growth system of claim 1, wherein the translucent ortransparent polyurethane polymer contains no phthalates.
 13. Thecontinuous growth system of claim 1, wherein the filtration systemcomprises at least one system selected from the group consisting of acoarse filter with a maximum particle flow permission limit of no morethan 5 microns; an activated charcoal filter to remove any organicmaterial; a fine filter with a maximum particle flow permission limit ofno more than 0.35 microns; and an ultraviolet light sterilizer todestroy any spores or bacteria that might get through the filtrationsystem.
 14. The continuous growth system of claim 1, further comprisingintroducing native phosphate ores comprising uranium into thedistribution system for the interaction with algae for capture of uranylions.
 15. The continuous growth system of claim 1, further comprisingintroducing rare earth elements into the distribution system for theinteraction with algae for capture of the rare earth elements.
 16. Thecontinuous growth system of claim 1, further comprising introducingcontaminated water comprising radioactive nuclides into the distributionsystem for the interaction with algae for recovery of isotopes ofcesium, strontium and plutonium.
 17. The continuous growth system ofclaim 1, wherein the continuous growth system is attached to anindustrial point source of CO₂ for capturing the CO₂ and converting itinto biomass.
 18. The continuous growth system of claim 1, wherein thecontinuous growth system is attached to a waste water treatment plant,wherein waste water comprising high levels of phosphorus and nitrogen isintroduced into the continuous growth system for maintaining the growthand reproduction cycle of the algae.
 19. The continuous growth system ofclaim 1, wherein microalgae are introduced for the production ofastaxanthin.
 20. The continuous growth system of claim 19, furthercomprising downstream processing for extraction of astaxanthin.